Modern day passenger vehicles include an increasing amount of electronics. Advances in technology have made it possible to incorporate a wide variety of systems onto a vehicle. For example, various sensor configurations have been developed to provide assistance or information to a driver regarding the environment surrounding the vehicle. Various object detection and sensing technologies provide parking assist and collision avoidance features, for example.
Advances in radio frequency signaling technology have enabled the development of sophisticated system-on-a-chip integrated circuits. The functionality required for environmental sensing or communications can be embodied in integrated circuit components. Example uses for such devices include automotive vehicle radar detection systems, robotics guiding systems and Wi-Fi data transfer.
Antennas for signal transmission may vary depending on the particular sensing or communication of interest. For example, low gain, broadband antennas are used for Wi-Fi communications and larger, high gain antennas are typically used for point-to-point data communications. Antennas useful for automotive radar systems typically fall between those two extremes. One type of antenna that has been developed that can be useful for vehicle-based systems is known as a substrate-integrated-wave guide (SIW). These devices are useful in the vehicle context because they typically possess high efficiency and are relatively low cost.
One challenge associated with utilizing SIWs for a vehicle-based sensing or communication system is associated with the connection between the integrated circuit components and the SIW. For example, microstrip or coplanar wave guide microwave transmission lines can provide an interface between the integrated circuit components and the SIW. Such connections include drawbacks, such as the requirement for a microwave component that matches the field configuration peculiar to each transmission line. The transition associated with such a microwave component increases microwave loss and introduces microwave reflections that may limit bandwidth and impact the ability to produce such systems. When a microstrip is used, bandwidth may be limited by the requirement for the ground connection to pass from the integrated circuit component connectors through the SIW substrate to a metal layer on that substrate. Such connections are typically made using a relatively expensive blind via process.